EarthLinked can make radiant hot water, domestic hot water, and forced air heating and cooling all from the same unit. This requires some modules that go with the heat pump unit, and knowledge on the installer's part to put that together. We've done it ourselves, and it works very well.

Hi Nick, I'm very interested in your project because I also live in New Hampshire (conway area) and have been investigating the same technology and have the same questions.

I noted that ECR advertises some high flow 2" flexible air ducts as well as air handlers on their site. One of my issues with ECR is that the technology they use doesn't allow for a variable speed compressor. I'm trying to design a solar system that is beefy enough to run the geo system and variable speed allows for a smaller start amp, at least that is my understanding.

Please keep the site posted on who you go with and why as it'd be very helpful to learn from your bidding process. BTW, it is also my understanding that, cost issue aside, there is no problem using the ECR technology for both radiant and forced air systems.

Not speaking as an HVAC expert, but am learning basics thanks to this forum. Not recommending any of the following, just recounting what I've read. Another combo source is Hydro-Temp which patented a system in 1980 and is located in Arkansas. Richard Rue, who many know does load calculations in TX, recommends them. Econar is located in Minnesota and claims to be a cold climate geothermal heat pump. Might consider since you're in New Hampshire. I know someone with a ClimateMaster open system who has had to replace a flowmeter due to the mineral content of the well water. Make sure you're well water wouldn't cause mineral buildup problems for you.

I am leaving for Florida tomorrow morning for 10 days, and I won't have internet.  Time to roast the bones.  I just don't want anyone to think I checked out.  Three designer/installers now have my house plans and know of my radiant/air hybrid goal.  Perhaps I will have some good info when I get back.  I will certainly spill my guts.

Bob, we have to talk.  I think your idea of geo for the heat/cooling source AND solar to run the compressors and pumps is awesome.  Talk about being off the grid!  Is your house oriented properly to take full advantage?  Mine is terrible, being oriented due north for the view.  Now you have me thinking.....

I will check in on my return.  Take care all.

Nick

Just a word of caution on coupling solar and PV (which you're probably already aware of) in terms of energy efficiency it is likely a losing proposition. If the solar cell is only 15% efficient, and you use it to run a heat pump with a COP of 3.5, you're effectively getting a "sun to heat" efficiency of about 50%. You can get close to this with a solar hot water collector for a fraction of the cost.

Of course there are a lot of other financial and engineering issues to consider, so it might make sense for a particular application.

Nick, we'll talk when you get back, have fun.

With regard to the solar issue. I'm planning to use a solar hot water system for part of the year perhaps augmented by either on demand or electric tank for the winter months. I'm using the solar PV to power the house and among other items, the geo-thermal. Of course the system has to be engineered for the loads and yes, voltage drop and start amps are an issue. I may end up having to make concessions here because the PV system could be cost prohibitive, I know it'll be pretty damn spendy as it is.

Hello,
Thanks for this great conversation. We're prepping to build in NW Indiana, in the dunes near Chicago and we've got a bid for a waterfurnace synergy 3 system to supply both radiant heat on three floors and as well as forced air on two. Today a competing company was dissing these combination units claiming that they have proven themselves to be unreliable. From what I've read here the compressors work harder to get the temps needed for radiant heat, but is there anything inherently unreliable about these systems?
Thanks

I have heard the same thing from one of my three potential geo contractors.  He has completely dissed combo units.  Come to find out, he only uses Climatemaster units and.....surprise surprise.....Climatemaster does not make a combo unit.

Reliability and a proven track record are key for me.  I will not venture forth without with something unproven or unreliable.  To the point were I will give up on radiant completely if I have to.

Perhaps combo units are just a little too cutting edge?

If you're looking at PV just for the geo then I'd guess that needs around a 4 kw system. A system like this, owner installed, would run at best $20K. Now stick your normal kwh usage and a system like this would double. Remember, these PV systems won't produce what you need during the bad months, Nov.-Feb, therefore they must take excess kwh produced during the summer and apply the credits during the winter months when your geo is cranking. None of this is cheap but for those of us that believe energy could get very expensive and possilby hard to get, it's all there is other than chopping down all the trees and burning them. Solar hot water is very effective for DHW and geo supply. SHW won't do your DHW during the bad months but would really work well with the geo. Nick, where in NH are you from ? I used to live in Exeter.

Understand that at some point in the future you won't be able to sell back power to the utility companies at retail rates. When sell back hits a certain point the power companies will not be able to sustain retail purchase of power. So enjoy it while it lasts, and hope that not too many people take advantage of it or the gravy train will crash. When it happens depends on how fast people take advantage of it.

Scary thought but I wouldn't doubt it.  We have an energy group that had a Central Maine Power big wig do a presentation about the present and future outlook of electrial energy in the Northeast.  This guy (if you can believe him) said that they're going to have real issues with supplying enough energy in the next ten years and that they project brown outs no matter what they do in the next few years to try to stop it. Permitting, capital and lead times were big issues along with growing usage. Time will tell.

Northeast includes Michigan. The way I see it with all the business moving out of our state and all the manufacturing plants that keep closing there should be an abundance of of electrical power. In years past my work place would shutdown on high electrical demand days during the summer under a special contract with DTE energy. They shutdown a major automotive plant not to far from us last spring. Since that, even on very hot days they keep us running. I expect with this plant closing that power usage has dropped to the point they no longer need us to cutback.

My question is, where is this added demand going to come from?  It would seem to me that some of DTE energy could be routed up to Maine.  The rate we are going in this state we woun't be needing it!

I realize I'm over 3 years late on this topic, but I found it while trying to confirm that radiant + geothermal was the right way to go.

NickB - How did your system turn out?

In our current home, we did radiant in the slabs and forced air on the first & second floors. It's a big house, so radiant loads are handled by a boiler while geothermal handles the forced air upstairs. Oddly enough, the basement is 65 year round, with NO heat or A/C used. If I were trying to work in an office at that temp, I'd need to heat it to 72, but 65 is great for a rec room, bar and storage. The unfortunate thing is, we have radiant in the house, but we don't use it, so I don't know what it's like! I will say that geothermal forced air is nicer than regular forced air - it runs more often but at a lower temp so you have very even heating - this is one of the benefits I hear about radiant. The other benefits I hear about radiant are plentiful: Operating costs; Warm floors & furniture but the air is cooler - when you're sitting still you're comfortable, when you're running around the house you're still comfortable; Warm feet in the morning or after a shower; No dank smell from moisture in your basement; etc.

In the new house, we're downsizing and want to simplify HVAC considerably. The entire first floor is pre-cast concrete planks (like Span-Crete) with a radiant slab on top. The 2nd floor is 2 bedrooms and a bathroom, and is heated via forced air ducts, which will also carry the A/C. There is ductwork in the 3 main rooms (open concept) on the main floor for A/C, but radiant will heat that mega-slab, with the help of some passive solar tempering. (apparently it's not passive solar "heating" unless you have an unreasonable number of windows facing south!) The idea is that the slab, as thermal mass, works as the core of the home, and the heat radiates down to the basement as well as up to the first floor. Convection may carry some of the heat to the 2nd floor, but we didn't want to risk cold spots. Since the WaterFurnace will heat forced air without any extra equipment, we'll let the forced air and rising radiant fight it out with the thermostat as the referee. With so much thermal mass (the basement walls and floor are insulated from the outside (R-32) adding MORE thermal mass, and the house is SIP panels (R-40, R-60 roof) we should be able to run the HVAC at off-peak hours and experience only a few degree temp. swing.

A lot can happen in 3 years... does anyone have any experience with geothermal + radiant combo units... victories or horror stories?

I have a Hydro-Temp 4-ton combo unit. 1920 sq.ft. main floor, 1920 sq.ft. basement and garage.

Air main floor, radiant basement and garage. I would consider it a victory. 1 1/2 years running.

The most important thing I have learned about radiant and Geo is, use more tubing!! I installed the tubing 12" on center, wish I had gone 6-9" on center. You want to be able to send 80-90 degree water to the floor. The heat pump can make that temp very efficiently.

ChrisJ

We've installed a number of systems with both ducts and radiant.  The experience has been favorable for our clients.  In fact, having the ducted system as second stage heating is a good thing.  We've installed radiant with both DX and deep well water loops and both have worked well.  We do recommend the radiant be installed by a professional radiant contractor and include floor sensors and if necessary outside anticipators.  Proper controlsd are a must with radiant systems.

Good Luck

Paul
Total Green Geo
www.TotalGreenUS.com

Hello,

I don't post here very often, but only occasionally check the forums on my old topics.  I received a good amount of help on my system from folks here.
So I'll give you my data point.

I have a new house (finished 2009) with a water to water combined with hydronics and air handler. 

House is 3000 ft2, stick built, closed cell foam insulation, located in Michigan.  All 1st floor rooms have hardwood or tile and are hydronic.  Both upstairs baths are tile and hydronic.  The air handler is setup for whole house, but has an air zone valve that can shut off the 1st floor for heating.  Basement is concrete with hydronic.

I setup the hydronic to be as low a temp as possible.  The tubing is right below the floor coverings.  Tile beds are as low mass as I could get.  Could still be lower. 

The heat pump is a Climatemaster 3 ton R22 unit.  I couldn't get a de-superheater with the newer ones at the time. 

I have a 60k Btu propane boiler as a backup instead of electric.  The system as originally designed had a lot of major issues.  Wild overswings on temps, lack of capacity, etc.
We basically froze the first winter.   I believe most of my issues related to my installer.  He tried hard, but these systems are very very complex, and he just didn't have the experience necessary.  Being a degreed Mechanical engineer, and also out of money, I was able to salvage the system.  I started by buying Siegenthaler's major books to get educated.  I designed the system based on his basic principles.  I used a sort of modular approach to the new system.  I enjoyed fluids class in college though, so I'm sure that helped.

The new system made these changes -
The wild temp swings in the swing seasons (defined by large outdoor temp variations) were pretty much eliminated by moving to a two buffer tank system with automatic switchover valves for both air handler and heat pump.  One tank of hot, one tank of cold.  When outdoor temps go above 70, the heat pump automatically switches over to the cold tank and makes cold water.  When it drops below 70, the heat pump switches over to the hot tank and makes hot water.  The heat pumps' only job is to make hot or cold water and dump it into the appropriate tank.  It's function is tied exclusively to that.  It doesn't care what anything else in the system is doing. 

The hydronics are setup to only pull out of the hot tank, and function the same as any other hydronic system. 

The air handler is setup to pull from either hot or cold tank based on call for heat or A/C, and uses a automatic ball valve to switchover just as the heat pump.
It sends air to the upstairs only on heat call, and whole house on A/C call.

The heat pump de-superheater dumps into a pre-heat tank which then dumps into a 105 gallon solar/boiler hot water tank. 

The boiler finish heats the hot water for the house, and when a call for additional heat for the hot tank is needed, dumps heat into the hot tank.
The boiler starts heating the hot tank if the temp falls more than 5 degrees below setpoint.  This only happens if the heat pump runs out of capacity in the dead of winter.

Now my data point - My first winter, on the old system, we were averaging between 400-600 dollars a month electric, and used about 600 dollars of propane per month on average.
I was terrified that we were in deep deep trouble on our choices for heat.  I was convinced we'd be into a wood boiler in a year or two or bankrupt.

After the reconfigure, my typical bill is about 200-250 per month for electric, and about 200 gallons of propane PER YEAR. 

I think what really made the difference though is when I reconfigured the system for outdoor reset on both heating and cooling.  So my hot tank temps hit 120F only when it's 0F outside.  As temps outdoors rise, hot tank temp drops accordingly.  I think the reset curve is about 0.3, not sure.  So really, most of the time, my buffer setpoint is about 90F.  And believe me, that was a HUGE difference in cost to run vs 120F.   And likewise, in summer, my cold buffer tank setpoint goes down to 35-40F only when it's really hot out, otherwise it's up around 50F.  That saves much less energy, but it was only a software change, so it was trivial to implement.

The house is VERY VERY comfortable almost all the time.  My wife is very happy with the performance.  If mama aint happy, nobody is happy....

we notice the warm floors in the mornings or when it's cold outside, with a very gradual decline over the day as it warms outside.  It's just comfortable, quiet heat.

Now, not just anybody can implement this setup.  It's a lot of plumbing.  I have controls that needed to be programed.  It's PLC run.  It's like a big engineer's toy.

The thing I would recommend anyone who's NOT an engineer to do is find a very qualified guy to design and install your system.  I'm sure they're out there somewhere.
Just I didn't find one.  But I sure like the cost savings.  I beat everyone in the neighborhood.  Even the guys with houses half the size.  The only guy who beats me is the neighbor with a wood boiler.  And he burns about 12-15 full cords a year.  He's pretty much a full time woodcutter.  I get to watch tv.  Not sure who wins there... :)

Posted By 86turbodsl on 11 Nov 2011 01:45 PM
He's pretty much a full time woodcutter.  I get to watch tv.  Not sure who wins there... :)

Since you probably don't get splinters from the remote, I'd say you win. 

heat pumps' only job is to make hot or cold water and dump it into the appropriate tank

Note that heat pumps are really good at producing hot AND cold water at the same time. Would be more efficient than producing one and then the other from a source loop - at least until you have more than you need of either one.

Well, messing with the source side was not desirable as my source loop is 20% methanol. 

Not to mention that making cold and hot at the same time is only typical about 3 months a year.  It didn't seem worth it to attempt to optimize to that degree.

there's some recent articles available from Seigenthaler where he details a system that has a small heat pump that does what you describe.  It's a much larger system
than a normal residential home though.